Mobile communication towers are installed on various sites for increasing the network coverage for mobile communication systems. The base station equipment is normally located on a pad, typically a concrete pad directly under the tower or adjacent to the mobile communications tower. There is a direct metallic path from the mobile communications tower to the base station equipment ground bus, for protecting the mobile communications tower and associated costly communication equipment from earth faults caused by lightning and other power surges. When a fault occurs on the mobile communications tower, there is a distinct possibility of fault current and voltage transferring into the service neutral. Normal construction practices for installations do not always provide adequate protection to the tower and associated costly communication equipment.
As new demands for increasing the communication capabilities are placed on the mobile communication system, more mobile communications towers are built and/or upgraded in existing right-of-ways. Due to which fewer maintenance outages are accommodated and maintenance personnel are encountering new challenges in their work. For ensuring interruption free communication, the possible earth faults may be avoided by constantly measuring the earthing values and alerting the operator personnel regarding the possible outages. High earth values of the EGB (an acronym for “external ground bar”) and IGB (an acronym for “Internal ground bar”) may damage the mobile communications tower. Ultimately tower companies face a huge loss at the end of the year for maintenance and replacement of these components.
There are many devices commercially available in the market to monitor the earth values. But, soil resistivity changes with the location and therefore earth value also changes. A more advanced earth fault remote sensing apparatus in the market includes a permanently mounted control and display unit powered by an AC supply. However the power and control circuitry employed in the apparatus is complex and needs a power convertor circuitry for converting the AC power to DC power for operating the digital components including the microcontroller circuitry and display unit. Moreover the apparatus is permanently attached to the device to be protected and does not include a calibration mechanism for adjusting the reference earthing value of the microcontroller, as the earth resistivity depends on the soil and changes from place to place. Further, the apparatus is not portable as it is designed to use as a permanent attachment to the equipment to be protected. So there are no devices available which will monitor the earth values of the tower irrespective of the location remotely and capable of responding to changing soil resistance in a dynamic way.
Earth resistance varies with the soil resistivity. In order to check the earth value of the mobile communications tower and/or a similar office configuration that houses machines, a device that will work irrespective of location is required. Devices currently available in the market can't work irrespective of location without adjusting the reference value of the earthing. Some earth fault detectors are powered by a high operating voltage supply and are not efficient. The accurate earthing values of the mobile communications tower at different locations cannot be measured using existing devices. Existing devices and methods may apply a low electrode voltage. Many times such low electrode voltage may be required, since poor maintenance conditions may damage existing installations using a high voltage method. Moreover, existing devices do not have technology for early detection of possible earth faults which may be detected by measuring other parameters like soil moisture, regression trend and applying a predictive algorithm. In addition, existing devices in market cannot be employed for automatic and remote real time monitoring of earthing values associated with a large number of mobile communication towers because such large numbers would need a scalable alarm system specifically built for an alarm configuration of the large numbers instead of existing no-contact alarms in a cell tower location. These devices are heavy; measurement is independent of ground location. Further, these devices include complex circuitry and provide only intermittent manual operation, in addition to requiring a large enclosure for covering. Hence the devices are difficult to maintain and cannot be easily ported to a desired location.
U.S. Pat. No. 8,390,299 B2 discloses an Earth ground tester with remote control. The testing device comprises a main unit and a remote unit adapted to communicate with one another via a communication link. After setting the testing device up, according to the desired measurement technique, the measurement procedure may be carried out, and resulting measurement values are subsequently displayed on the remote unit. This allows a single operator to perform measurements while standing directly adjacent to an electrode, which is, for example, placed at a large distance from the main unit and/or other electrodes. This relieves the operator from constantly having to walk back and forth placing electrodes in different positions, and also obviates the need to return to the main unit of the testing device to consult a display and/or to change parameters or settings. The drawback with U.S. Pat. No. 8,390,229 B2 is that the measurement is not really remote. Further, the operator needs to make measurements manually and the device fails to collect readings from multiple locations. Still further, the '299 patent does not take into consideration; the change in soil resistivity from one location to another and also fails to map data collected onto a predictive, preventative and prescriptive system.
PCT publication WO 2010/104735 A1 discusses a device and method for detecting ground potential rise (sometimes hereinafter “GPR”), the method comprising positioning a first electrode and a second electrode at a distance from each other and extending into the Earth. The voltage of the first electrode and second electrode is attenuated by an attenuation factor creating an attenuated voltage. The true RMS voltage of the attenuated voltage is determined creating an attenuated true RMS voltage. The attenuated true RMS voltage is then multiplied by the attenuation factor creating a calculated true RMS voltage. If the calculated true RMS voltage is greater than a first predetermined voltage threshold, a first alarm is enabled at a local location. If user input is received at a remote location acknowledging the first alarm, a first alarm acknowledgment signal is transmitted. The first alarm acknowledgment signal is then received at which time the first alarm is disabled. However, this application fails to work with low electrode voltage applied to ground and map data collected onto a predictive, preventative and prescriptive mechanism for equipment by taking into account the other sensor and/or manual parameters (like soil test result, soil humidity) along with time series progression of the increasing resistance value.
U.S. Pat. No. 8,405,940 B2 discloses a system and method for generator ground fault protection. A generator winding-to-ground fault detection system is discussed, the system includes a signal injection source in electrical communication with a winding of an electric power generator via an injection transformer. The winding may be coupled to ground via a winding-to-ground path and the signal generation source may generate an injection signal capable of being injected to the winding using the injection transformer. The disclosed system may further include a protection module in communication with the signal injection source and the electric power generator configured to receive the injection signal and a signal relating to the current through the winding-to-ground path respectively to determine the occurrence of a winding-to-ground fault condition based at least in part on the injection signal and the signal relating to the current through the winding-to-ground path. Similar to WO 2010/104735 A1, this application fails to work with low electrode voltage applied to ground and map data collected onto a predictive, preventative and prescriptive mechanism for equipment by taking into account the other sensor and/or manual parameters (like soil test results, soil humidity) along with time series progression of the increasing resistance value.
Thus, there still exists a need for a system and method for detecting earth faults that can be used with the mobile communication towers and/or similar machine housing set-ups, to protect the towers and associated communication equipment from possible earth faults. There exists a need for a system and method for detecting earth faults that could provide early warning of failure from associated soil condition and time series progression of earth resistance value. Moreover, there exists a need for a system that would provide accurate readings in accordance with corresponding ground locations by accommodating soil condition parameters. Further, there exists a need for a system that would incorporate smaller circuit and power supply in a small enclosure with far reduced electrode voltage for soil resistance measurement. Moreover, there is also a need for a system that would enable automatic and remote monitoring of earthing value for any number of towers located in various geographic locations.
It is evident from the discussion of the aforementioned prior art that none of them pave way for the predictive (early warning) and preventive maintenance of an earthing system through machine learning of earth resistance time series values, alarms and soil condition of various locations.
Further, early warning or prediction of failure of Earth resistance values (For example: when earthing resistance crosses a 6 Ohm value) reduces the risk associated with maintenance of mobile towers as it prevents “run to failure” model. The prior arts merely provides an alarm for “run to failure” model but fails to suggest regarding early warning or predictive maintenance of Earth resistance values. The prior arts also fails to suggest a predictive engine that incorporates soil parameters obtained from sensor value or known test results of the soil. Therefore, there is a need in the art for a solution to the aforementioned problem.